Ammonium carbamate is not an available commercial product. It occurs as an intermediate product in the production of urea, and apparently it has never been separated and removed from urea plants due to the lack of any market.
A patent for using ammonium carbamate as a deicer was issued to Hansen as U.S. Pat. No. 4,698,173 on Oct. 6, 1987. This deicer does not corrode steel or aluminum, and instead of being toxic to plant life as are commonly used highway deicers, the contained nitrogen actually promotes plant growth. Tests at the Utah Department of Transportation also demonstrated that an ammonium carbamate deicer dramatically reduced the freezing damage to concrete. In 1976, the Environmental Protection Agency estimated that the use of nine million tons of salt per year as a deicer, costs the public about five billion dollars per year at a cost of about $555 per ton. With the potential money to be saved by using a deicer of moderate price and which does not damage the environment, and with a potential market of about nine million tons per year, it became evident to the present inventor that there would be numerous benefits if the ammonium carbamate could be commercially produced. Furthermore, urea production plants are a logical available source of ammonium carbamate.
The process of removing ammonium carbamate from a urea plant presented several problems, however. One of the principle problems was that it existed in the urea production plant under high temperature and pressure. A method had to be devised for removing the ammonium carbamate from the water and ammonia solvents it is in solution with and converting it to a useable state, which is crystalline in this case.
A second problem to be solved was to devise a method of making the ammonium carbamate crystals into granules or pellets which can be distributed on roads. In attempting to solve this problem, the present inventor discovered that the crystals produced contained too much moisture to be pelletized or granulated and so a method had to be devised to remove the water from the crystals. In addition, after learning how to remove the water from the crystals, a method of granulating or pelletizing the crystals had to be devised. Finally, a binder that would hold the pellets together, as well as a technique to keep the pellets stable for subsequent use, were also needed.